Similar mount and connection.

For me the most unreliable part has been the USB serial driver (FTDI) and USB to RS-232 device.

I used a 2-port USB-to-serial device for years (Exatron? something like that), then bought a new USB-to-serial (one port) cable last year. That one failed fairly quickly, and I went back to my tried-and-true device which I never should have replaced.

Some troubleshooting techniques that have been useful:

On Windows, open "Device Manager" and look at the USB connections. You might try uninstalling the serial port driver, and let it reinstall when you plug in the adapter to the USB port.

You might also try unplugging the serial converter and plugging it into a different USB port. I've had trouble where it would only work if you plugged it into the same port you used last time.

Someone else might have more precise instructions. I will say I'm really enjoying the reliable wired ethernet connection to the CP4 on my 1100, but the Mach1/CP3 still gets most of my observing time.

Mojo

[Edited Message Follows]

Mach1GTO, CP3 controller.  I cannot connect to my mount.  I've uninstalled-reinstalled the latest V2 driver and FTDI driver.  I installed the latest version of APCC.  I've unplugged-replugged all cables, several times.  This gear has always been picky about turning on the mount power before turning on the computer, so I've been diligent about shutting everything down, letting it sit a bit, then restarting.the mount first, then the computer.  I went through something like this during the winter, but plugging the FTDI adapter into a different USB port got it working that time.  No joy this time.  Device Manager says the FTDI driver is working correctly.  Should I just assume that any or all pieces, from the FTDI controller to the CP3 driver, are defective and need to be replaced?  I'm at a loss to explain this or to come up with a solution.  I'm looking for suggestions about something I've overlooked.